Dysbiosis in gut microbiota causes disequilibrium in energy homeostasis that ultimately leads to obesity. Numerous mechanisms have been reported by which gut microbiota induces obesity in experimental models.
Link to Publication: https://www.ncbi.nlm.nih.gov/pubmed/28421057
Dahiya DK, et al. Gut microbiota modulation and its relationship with obesity using prebiotic fibers and probiotics: A review. Front Microbiol. 2017;8:563.